<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>选择器</title>
    <style>
        /*
    标签选择器
        */
        div {
            color: red;
            font-size: 50px;
        }

        /*
            ID 选择器
        */
        #div2 {
            color: blue;
            font-size: 30px;
        }

        /*
            class 选择器
        */
        .style1 {
            color: green;
            border: 10px solid black;
        }
    </style>
</head>
<body>
<div>div元素1</div>
<div id="div2" class="style1">div元素2</div>
<div>div元素3</div>
<div class="style1">div元素4</div>
<div class="style1">div元素5</div>
<div class="style1">div元素6</div>
</body>
</html>